Glass Working Exercises 



109 



FIG. 100. Sealing of 

 eudiometer wires. 



to cool, which must take place slowly, and finally wrap the tube 

 up in cotton-wool until perfectly cold. 



Should the wires not be exactly opposite each other, at the 

 finish, they may be brought into position by a touch with a 

 hooked wire, but this should not be attempted until cooling is 

 complete. 



The enamel glass serves two purposes 



1. It fuses a little more readily than ordinary glass, and is 

 therefore easier to work. 



2. Its colour being distinctive, the pro- 

 gress of the junction is more easily followed. 



The wires should be sealed into the 

 tube in the shape indicated by the sketch 

 A, Fig. 100. Purchased apparatus is fre- 

 quently of the type B, which allows an 

 inserted wire to pull open the loop of 

 platinum wire, and strain the portion which 

 enters the glass, causing it to break off after 

 being used a few times. Both ends of the loop should therefore 

 enter the glass, and this will be found to be the case if the instruc- 

 tions above are carefully followed. 



EXERCISE 15. To make a condenser jacket. 



Select a piece of 27-25 mm. glass tubing, cut off about 30 cms., 

 with ends at right angles to the axis of the tube. Border these ends 

 as before, and fit a cork to one end. 



Prepare two side tubes, by blowing a bulb at the end of each, 

 and, heating beyond A, Fig. ioi,blow a second large and light one. 

 When this is removed, we have an 

 opened tube, with gradually thin- 

 ning edges. 



Commence by heating in a "cool" 

 flame the whole of the glass where 

 the side tube is to be inserted, ro- 

 tating evenly until the whole cylinder 

 of glass is hot at this place. With 

 a small flame now heat strongly one 

 point only, and gradually blow it 

 out as in Exercise 7 for a T joint. 



Insert a second cork into the jacket, and make the right-angled 

 joint as in Exercise 7, wrapping in cotton-wool immediately the 

 joint is completed. When this is quite cold, insert a second piece 



FIG. 101. 



